[BioC] limma question

[Julia Engelmann]

Hello all,

I am using limma on Affymetrix data and I read and followed the User's Guide 
so far,  but one thing is still not clear to me:
Are the M-Values returned by the toptable- command estimated log2-fold 
changes? I know typing "?toptable"  in R says "M: estimate of the effect or 
the contrast", but I don't understand what that means.
If they aren't, where can I get fold changes for my data?

I have 4 untreated and 4 treated experiments, my R code is:
design<- cbind(c(1,1,1,1,1,1,1,1),c(0,0,0,0,1,1,1,1))
fit   <- lm.series(exprs(Set),design)
eb    <- ebayes(fit)
result <-toptable(coef=2,number=300,genelist=data,fit=fit,adjust="fdr")

Thanks a lot for your help,
Julia